Matthew 5:33–35
For this reason he forbids us to swear by heaven and earth: that we not give creation a dignity beyond creation and make it a god. Those who swear, he says, “swear by the greater,” (Hebrews 6:16) as the apostle said.
He also forbids the oath by “Jerusalem,” (Matthew 5:35) because earthly Jerusalem is a type of the Jerusalem above, and God swears by himself alone — that is, by his own glory. Since that likeness surpasses us, we ought not swear by ourselves or by our own glory. We are not free as God is; we are under God’s authority.
Greek
∆ιὰ τοῦτο κωλύει ἡμᾶς ὀμνύναι κατὰ τοῦ οὐρανοῦ καὶ τῆς γῆς, ἵνα μὴ δῶμεν τῇ κτίσει τὸ ὑπὲρ τὴν κτίσιν ἀξίωμα θεοποιοῦντες αὐτήν· οἱ γὰρ ὀμνύντες, φησίν, "κατὰ τοῦ μείζονος ὀμνύουσιν" ὡς ὁ ἀπόστολος ἔφη. ἀπαγορεύει δὲ καὶ τὸν κατὰ τῆς "Ἰερουσαλὴμ" ὅρκον, ἐπειδὴ ἡ ἐπίγειος "Ἰερουσαλὴμ" τῆς "ἄνω Ἰερουσαλὴμ" τύπος ἐστὶ καὶ καθ' ἑαυτοῦ μόνου ὀμνύει ὁ θεός, ὅ ἐστι τῆς ἰδίας δόξης. διὸ ὡς ὑπερ βαινούσης ἡμᾶς τῆς ὁμοιότητος οὐκ ὀφείλομεν καθ' ἑαυτῶν ἤτοι τῆς ἑαυτῶν ὀμνύειν δόξης· οὐ γὰρ ἐλεύθεροί ἐσμεν ὡς ὁ θεός, ἀλλ' ὑπὸ τὴν τοῦ θεοῦ ἐσμεν ἐξουσίαν.